Store a pointer to the return value in a static alloca and let the debugger use that
as the variable address for NRVO variables.
Subscribers: hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D63361
llvm-svn: 363952
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a53ca8f..dbe582c 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3835,7 +3835,8 @@
llvm::DILocalVariable *CGDebugInfo::EmitDeclare(const VarDecl *VD,
llvm::Value *Storage,
llvm::Optional<unsigned> ArgNo,
- CGBuilderTy &Builder) {
+ CGBuilderTy &Builder,
+ const bool UsePointerValue) {
assert(DebugKind >= codegenoptions::LimitedDebugInfo);
assert(!LexicalBlockStack.empty() && "Region stack mismatch, stack empty!");
if (VD->hasAttr<NoDebugAttr>())
@@ -3940,6 +3941,16 @@
}
}
+ // Clang stores the sret pointer provided by the caller in a static alloca.
+ // Use DW_OP_deref to tell the debugger to load the pointer and treat it as
+ // the address of the variable.
+ if (UsePointerValue) {
+ assert(std::find(Expr.begin(), Expr.end(), llvm::dwarf::DW_OP_deref) ==
+ Expr.end() &&
+ "Debug info already contains DW_OP_deref.");
+ Expr.push_back(llvm::dwarf::DW_OP_deref);
+ }
+
// Create the descriptor for the variable.
auto *D = ArgNo ? DBuilder.createParameterVariable(
Scope, Name, *ArgNo, Unit, Line, Ty,
@@ -3958,9 +3969,10 @@
llvm::DILocalVariable *
CGDebugInfo::EmitDeclareOfAutoVariable(const VarDecl *VD, llvm::Value *Storage,
- CGBuilderTy &Builder) {
+ CGBuilderTy &Builder,
+ const bool UsePointerValue) {
assert(DebugKind >= codegenoptions::LimitedDebugInfo);
- return EmitDeclare(VD, Storage, llvm::None, Builder);
+ return EmitDeclare(VD, Storage, llvm::None, Builder, UsePointerValue);
}
void CGDebugInfo::EmitLabel(const LabelDecl *D, CGBuilderTy &Builder) {